// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_NORMAL_OCTAHEDRON_TRANSFORM_BASE_H_
#define DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_NORMAL_OCTAHEDRON_TRANSFORM_BASE_H_

#include <cmath>

#include "draco/compression/attributes/normal_compression_utils.h"
#include "draco/compression/config/compression_shared.h"
#include "draco/core/bit_utils.h"
#include "draco/core/macros.h"
#include "draco/core/vector_d.h"

namespace draco {

// Base class containing shared functionality used by both encoding and decoding
// octahedral normal prediction scheme transforms. See the encoding transform
// for more details about the method.
template <typename DataTypeT>
class PredictionSchemeNormalOctahedronTransformBase {
  public:
    typedef VectorD<DataTypeT, 2> Point2;
    typedef DataTypeT DataType;

    PredictionSchemeNormalOctahedronTransformBase() {}
    // We expect the mod value to be of the form 2^b-1.
    explicit PredictionSchemeNormalOctahedronTransformBase(
        DataType max_quantized_value) {
        this->set_max_quantized_value(max_quantized_value);
    }

    static constexpr PredictionSchemeTransformType GetType() {
        return PREDICTION_TRANSFORM_NORMAL_OCTAHEDRON;
    }

    // We can return true as we keep correction values positive.
    bool AreCorrectionsPositive() const {
        return true;
    }

    inline DataTypeT max_quantized_value() const {
        return octahedron_tool_box_.max_quantized_value();
    }
    inline DataTypeT center_value() const {
        return octahedron_tool_box_.center_value();
    }
    inline int32_t quantization_bits() const {
        return octahedron_tool_box_.quantization_bits();
    }

  protected:
    inline void set_max_quantized_value(DataTypeT max_quantized_value) {
        DRACO_DCHECK_EQ(max_quantized_value % 2, 1);
        int q = bits::MostSignificantBit(max_quantized_value) + 1;
        octahedron_tool_box_.SetQuantizationBits(q);
    }

    bool IsInDiamond(DataTypeT s, DataTypeT t) const {
        return octahedron_tool_box_.IsInDiamond(s, t);
    }
    void InvertDiamond(DataTypeT *s, DataTypeT *t) const {
        return octahedron_tool_box_.InvertDiamond(s, t);
    }

    int32_t ModMax(int32_t x) const {
        return octahedron_tool_box_.ModMax(x);
    }

    // For correction values.
    int32_t MakePositive(int32_t x) const {
        return octahedron_tool_box_.MakePositive(x);
    }

  private:
    OctahedronToolBox octahedron_tool_box_;
};

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_PREDICTION_SCHEMES_PREDICTION_SCHEME_NORMAL_OCTAHEDRON_TRANSFORM_BASE_H_
